The invention concerns a device and a method for non-contact measurement of an offset of the functional components of a guideway of a magnetic levitation train driven by a linear motor by means of at least one optical triangulation system that is movable along the guideway.
The invention concerns thus a laser-optical sensor for non-contact detection and measurement of the position of the motor winding in the stator pack, the relative position of the stator packs on the guideway of the magnetic levitation train and/or the vertical or horizontal offsets of the functional components of the magnetic levitation vehicle, namely based on the principle of optical triangulation.
The principle of triangulation uses the effect of light scattering of an illumination beam that impinges perpendicularly onto a surface in that the diffusely reflected light at a certain observation angle is received by an opto-electric sensor element. The position of the light spot that is imaged on the sensor element is evaluated for determining the distance relative to the measured object. The prerequisite is that the object surface is not to 100% planar-reflective (i.e., a mirror) because then the course of light will follow the law of reflection and an observation at an inclined viewing angle is not possible. In general, the scattering behavior of an object depends on its surface properties and the wavelength of the light. Conventionally, in case of triangulation the opto-electronic sensor element (e.g. CCD sensor) is located in the image plane of a receiving objective and is usually positioned at an angle of between 30 and 45° relative to the illumination beam. A displacement of the measuring point on the object in the direction of the illumination beam has the result that, according to the laws of optical imaging, the position of the pixel will move in the observation plane. As a measured value, the position of the pixel is detected.
Systems are known that, by means of optical triangulation by using industrial laser sources, have attempted reference measurements in regard to the precise position of the motor winding in the stator packs of the magnetic levitation train, in particular in connection with the Transrapid. The measurements performed by this method by means of triangulation using industrial laser sources as well as reference measurements of the stator packs/motor winding bottom edge relative to the attachment surfaces of the functional components (e.g. stator support) for the purpose of detection of the motor winding position have not delivered the desired results:                The possible measuring speed as a result of the methodology was only 1-2 km/h.        The measuring precision, as a result of the selection of reference surfaces and the additive effect of the manufacturing tolerances, was too small and was in the range of >4 mm.        The measurements under adverse weather conditions, for example, fog, rain, provided imprecise values.        The vibrations of the measuring vehicle upon passing across the joints of the supports falsified locally the measuring results.        
Moreover, the method and the device with respect to the application were limited to the detection of the position of the motor winding and not suitable for further important applications in connection with the Transrapid, such as:
As a quality inspection and approval, inspection and approval measurements of the stator pack position and motor winding position after completed installation on the guideway supports exhibited too small a measuring precision in the range of >4 mm instead of <1 mm.
Periodic control of the position of the stator packs by means of the offset measurement between neighboring stator packs in order to determine possible damages on the attachment because the measuring precision with >4 mm instead of <1 mm was too small.                Control measurement of the offsets and torsion of the lateral guidance rails and/or gliding plane of the guideway supports at the support junction as a result of support settling and/or support torsion. Control measurement of the offsets and torsion of the stator packs at the support junction as a result of support settling and/or support torsion.        Possible integration of the measuring systems directly into the maglev vehicle because the measuring frequency was much too low.        
In conclusion, the use of a method and device according to the prior art is:                Uneconomical because of the long time it takes to carry out the measurements and not precise enough.        Only suitable to a limited extent because functional only in good weather conditions.        Unsuitable for covering several required measuring functions of the Transrapid.        
For this reason, several devices with different technologies that inspect the system at different times are required for covering all required measuring functions.